als-statistics/tests/golden/edge-rng.test.js

Modular JS statistics toolkit for Node.js and the browser: descriptive stats, correlations (Pearson/Spearman/Kendall), t-tests & ANOVA (Student/Welch), reliability (Cronbach’s alpha), regression (linear/logistic), clustering (DBSCAN/HDBSCAN), and table/co

import test from 'node:test';
import assert from 'node:assert/strict';
import { makeRng } from './_rng.js';

test('rng: deterministic by seed', () => {
  const A = makeRng('seed-1');
  const B = makeRng('seed-1');
  const a = Array.from({length:100}, () => A.rand());
  const b = Array.from({length:100}, () => B.rand());
  assert.deepEqual(a, b);
});

test('rng: range is [0,1) and never 1', () => {
  const R = makeRng('edge-range');
  for (let i=0;i<2000;i++) {
    const x = R.rand();
    assert.ok(x >= 0 && x < 1, `x in [0,1): ${x}`);
  }
});

test('rng: normal has mean ~ mu and sd ~ sigma (rough)', () => {
  const R = makeRng('norm-check');
  const mu = 3.0, sd = 2.0;
  const arr = R.normal(mu, sd, 5000);
  const mean = arr.reduce((s,x)=>s+x,0)/arr.length;
  const variance = arr.reduce((s,x)=>s+(x-mean)*(x-mean),0)/(arr.length-1);
  const sdev = Math.sqrt(variance);
  assert.ok(Math.abs(mean - mu) < 0.1);
  assert.ok(Math.abs(sdev - sd) < 0.15);
});